作者：?QIanQ
原文：https://blog.csdn.net/study_deer/article/details/78606769
程序启动的第一阶段：
G:\u-boot-2010.06\arch\arm\cpu\hi3518ev200\start.S
.globl _start
_start: b reset
reset:
/*
* set the cpu to SVC32 mode
*/
mrs r0, cpsr
bic r0, r0, #0x1f
orr r0, r0, #0xd3
msr cpsr,r0
/*
* we do sys-critical inits only at reboot,
* not when booting from ram!
*/
/*
* flush v4 I/D caches
*/
mov r0, #0
mcr p15, 0, r0, c7, c7, 0 /* flush v3/v4 cache */
mcr p15, 0, r0, c8, c7, 0 /* flush v4 TLB */
/*
* disable MMU stuff and caches
*/
mrc p15, 0, r0, c1, c0, 0
bic r0, r0, #0x00002300 /* clear bits 13, 9:8 (--V- --RS) */
bic r0, r0, #0x00000087 /* clear bits 7, 2:0 (B--- -CAM) */
orr r0, r0, #0x00000002 /* set bit 2 (A) Align */
mcr p15, 0, r0, c1, c0, 0
/*
* read system register REG_SC_GEN2
* check if ziju flag
*/
ldr r0, =SYS_CTRL_REG_BASE
ldr r1, [r0, #REG_SC_GEN2]
ldr r2, =0x7a696a75 /* magic for "ziju" */
cmp r1, r2
bne normal_start_flow
mov r1, sp /* save sp */
str r1, [r0, #REG_SC_GEN2] /* clear ziju flag */
/* init PLL/DDRC/pin mux/... */
ldr r0, _blank_zone_start
ldr r1, _TEXT_BASE
sub r0, r0, r1
ldr r1, =RAM_START_ADRS
add r0, r0, r1
mov r1, #0x0 /* flags: 0->normal 1->pm */
bl init_registers /* init PLL/DDRC/... */
程序启动的第二阶段：
arch/arm/cpu/hi3518ev200/lowlevel_init_svb.s
程序启动的第三阶段：
G:\u-boot-2010.06\common\main.c
void main_loop (void)
{
}